Sustainable Regeneration of High-Performance Li_{1- x}Na _xCoO₂from Cathode Materials in Spent Lithium-Ion Batteries

With the wide implication of lithium-ion batteries (LIBs), the recycling of spent LIBs has generated strong concern in alleviating resource shortage and environmental pollution. In this work, the Li1-xNaxCoO2 (x = 0, 0.01, 0.03, and 0.05) cathode materials with structural repair and electrochemical performance improvement were obtained from degraded LiCoO2 cathodes (Li loss of >50% and capacity reduction of about 65%) in combination with relithiation regeneration and modification. Compared with regenerated LiCoO2 (RLCO) and commercial LiCoO2 (CLCO) materials, the Li1-xNaxCoO2 cathodes show a neat and ordered layered structure, better discharge capacity, and cycle stability, especially at high current density and high voltage. The initial discharge capacities of Li0.99Na0.01CoO2 (NLCO0.01) and RLCO are 151.5 and 149.4 mA h g-1 at the rate of 1C, respectively, which is almost three times higher than that of degraded LiCoO2 (50.5 mA h g-1). Moreover, the capacity retention rate after 100 cycles of NLCO0.01 at the rate of 10C is as high as 87.6%, vastly superior to the 63.2 and 54.2% retention rates of RLCO and CLCO, respectively. The excellent rate performance and cycle ability are attributed to the expansion of lithium layer spacing caused by sodium-ion doping with a larger radius and faster Li+ diffusion kinetics in the NLCO0.01 sample. This work provides a simple and effective strategy to regenerate and modify spent cathode materials, which provides a reference for the disposal of spent LIBs henceforth.